scripts/shini.sh
# shini - compatible INI library for sh
#
# This code is released freely under the MIT license - see the shipped LICENSE document.
# For the latest version etc, please see https://github.com/wallyhall/shini
#

# Solely for the purpose of portable performance, this script breaks good practice to
# avoid forking subshells.  One such good practice is avoiding global variables.
# This variable is used to carry non-numeric results from functions to the caller.
# Alternatively an echo and "$(...)" approach could be used, but is significantly slower.

shini_setup()
{
    if [ -n "$ZSH_VERSION" ]; then
        RESTORE_OPTS=$(set +o)
        # Enable BASH_REMATCH for zsh
        setopt KSH_ARRAYS BASH_REMATCH
    fi
}

shini_teardown()
{
    [ -n "$ZSH_VERSION" ] && eval "$RESTORE_OPTS"
}

shini_function_exists()
{
    type "$1" > /dev/null 2>&1
    return $?
}

shini_regex_match()
{
    # $KSH_VERSION (I'm told) only exists on ksh 93 and above, which supports regex matching.
    if [ -n "$BASH_VERSINFO" ] && [ "$BASH_VERSINFO" -ge 3 ] || \
       [ -n "$ZSH_VERSION" ] || \
       [ -n "$KSH_VERSION" ]; then
        [[ "$1" =~ $2 ]] && return 0 || return 1
    fi

    printf '%s' "$1" | grep -qe "$2"
    return $?
}

shini_regex_replace()
{
    if [ -n "$BASH_VERSINFO" ] && [ "${BASH_VERSINFO}" -ge 3 ] || \
       [ -n "$ZSH_VERSION" ]; then
        [[ "$1" =~ $2 ]] && shini_retval=${BASH_REMATCH[1]} || shini_retval="$1"
        return 0
    fi

    shini_retval="$(printf '%s' "$1" | sed -E "s/$2/\1/")"  # If you have isses on older systems,
    # it may be the non-newer POSIX compliant sed.
    # -E should be enabling extended regex mode portably.
}

# @param inifile Filename of INI file to parse
# @param postfix Function postfix for callbacks (optional)
# @param extra Extra argument for callbacks (optional)
shini_parse()
{
    shini_parse_section "$1" '' "$2" "$3" "$4" "$5"
}

# @param inifile Filename of INI file to parse
# @param section Section to parse (or empty string for entire file)
# @param postfix Function postfix for callbacks (optional)
# @param extra Extra argument for callbacks (optional)
shini_parse_section()
{
    shini_setup
    # ********

    RX_KEY='[a-zA-Z0-9_\-\.]'
    RX_VALUE="[^;\"]"
    RX_SECTION='[a-zA-Z0-9_\-]'
    RX_WS='[ 	]'
    RX_QUOTE='"'
    RX_HEX='[0-9A-F]'
    POSTFIX=''
    SKIP_TO_SECTION=''
    EXTRA1=''
    EXTRA2=''
    EXTRA3=''
    SECTION_FOUND=-1
	
	if [ $# -ge 2 ] && [ ! -z "$2" ]; then
        SKIP_TO_SECTION="$2"
    fi
	
    if [ $# -ge 3 ] && [ ! -z "$3" ]; then
        POSTFIX="_$3"
    fi
	
    if [ $# -ge 4 ] && ! [ -z "$4" ]; then
        EXTRA1="$4"
    fi
	
    if [ $# -ge 5 ] && [ ! -z "$5" ]; then
        EXTRA2="$5"
    fi
	
    if [ $# -ge 6 ] && [ ! -z "$6" ]; then
        EXTRA3="$6"
    fi
	
    if ! shini_function_exists "__shini_parsed${POSTFIX}"; then
        printf 'shini: __shini_parsed%s function not declared.\n' "${POSTFIX}" 1>&2
        exit 255
    fi

    if [ $# -lt 1 ]; then
        if shini_function_exists "__shini_no_file_passed{$POSTFIX}"; then
            "__shini_no_file_passed${POSTFIX}" "$EXTRA1" "$EXTRA2" "$EXTRA3"
        else
            printf 'shini: Argument 1 needs to specify the INI file to parse.\n' 1>&2
            exit 254
        fi
    fi
    INI_FILE="$1"

    if [ ! -r "$INI_FILE" ]; then
        if shini_function_exists "__shini_file_unreadable${POSTFIX}"; then
            "__shini_file_unreadable${POSTFIX}" "$INI_FILE" "$EXTRA1" "$EXTRA2" "$EXTRA3"
        else
            printf 'shini: Unable to read INI file:\n  `%s`\n' "$INI_FILE" 1>&2
            exit 253
        fi
    fi

    # Iterate INI file line by line
    LINE_NUM=0
    SECTION=''
    while read LINE || [ -n "$LINE" ]; do  # -n $LINE catches final line if not empty
        # Check for new sections
        if shini_regex_match "$LINE" "^${RX_WS}*\[${RX_SECTION}${RX_SECTION}*\]${RX_WS}*$"; then
            shini_regex_replace "$LINE" "^${RX_WS}*\[(${RX_SECTION}${RX_SECTION}*)\]${RX_WS}*$" "\1"
            SECTION=$shini_retval

            if [ "$SKIP_TO_SECTION" != '' ]; then
                # stop once specific section is finished
                [ $SECTION_FOUND -eq 0 ] && break;
                
                # mark the specified section as found
                [ "$SKIP_TO_SECTION" = "$SECTION" ] && SECTION_FOUND=0;
            fi

            if shini_function_exists "__shini_parsed_section${POSTFIX}"; then
                "__shini_parsed_section${POSTFIX}" "$SECTION" "$EXTRA1" "$EXTRA2" "$EXTRA3"
            fi
			
            LINE_NUM=$((LINE_NUM+1))
	    continue
        fi
        
        # Skip over sections we don't care about, if a specific section was specified
        [ "$SKIP_TO_SECTION" != '' ] && [ $SECTION_FOUND -ne 0 ] && LINE_NUM=$((LINE_NUM+1)) && continue;
		
        # Check for new values
        if shini_regex_match "$LINE" "^${RX_WS}*${RX_KEY}${RX_KEY}*${RX_WS}*="; then
            shini_regex_replace "$LINE" "^${RX_WS}*(${RX_KEY}${RX_KEY}*)${RX_WS}*=.*$"
            KEY=$shini_retval
            
            shini_regex_replace "$LINE" "^${RX_WS}*${RX_KEY}${RX_KEY}*${RX_WS}*=${RX_WS}*${RX_QUOTE}{0,1}(${RX_VALUE}*)${RX_QUOTE}{0,1}(${RX_WS}*\;.*)*$"
            VALUE=$shini_retval
			
            if shini_regex_match "$LINE" "^0x${RX_HEX}${RX_HEX}*$"; then
                VALUE=$(printf '%d' "$VALUE")
            fi
			
            "__shini_parsed${POSTFIX}" "$SECTION" "$KEY" "$VALUE" "$EXTRA1" "$EXTRA2" "$EXTRA3"
						
            if shini_function_exists "__shini_parsed_comment${POSTFIX}"; then
                if shini_regex_match "$LINE" ";"; then
                    shini_regex_replace "$LINE" "^.*\;(.*)$"
                    COMMENT=$shini_retval
                    
                    "__shini_parsed_comment${POSTFIX}" "$COMMENT" "$EXTRA1" "$EXTRA2" "$EXTRA3"
                fi
            fi

            LINE_NUM=$((LINE_NUM+1))
            continue
        fi
		
        # Announce parse errors
        if [ "$LINE" != '' ] &&
          ! shini_regex_match "$LINE" "^${RX_WS}*;.*$" &&
          ! shini_regex_match "$LINE" "^${RX_WS}*$"; then
            if shini_function_exists "__shini_parse_error${POSTFIX}"; then
                "__shini_parse_error${POSTFIX}" $LINE_NUM "$LINE" "$EXTRA1" "$EXTRA2" "$EXTRA3"
            else
                printf 'shini: Unable to parse line %d:\n  `%s`\n' $LINE_NUM "$LINE"
            fi
        fi
		
        LINE_NUM=$((LINE_NUM+1))
    done < "$INI_FILE"

    # ********
    shini_teardown
}

# @param inifile Filename of INI file to write to
# @param section Section of INI file to write to
# @param variable Variable name to add/update/delete
# @param value Value to add/update, do not specify to delete
shini_write()
{
    shini_setup
    # ********

    # This is not yet optimised (early write support only) - 
    # We actually re-parse the entire file, looking for the location in which to
    # write the new value, writing out everything we parse as-is meanwhile.

    # Declare the following if you want particular behaviour (like skipping
    # broken INI file content or handling an unreadable file etc).
    #  __shini_no_file_passed__writer()
    #  __shini_file_unreadable__writer()
    #  __shini_parse_error__writer()
    
    # Writer callbacks, used for writing the INI file content
    __shini_parsed_section__writer()
    {
        # Validate the last section wasn't the target section
        if [ "$LAST_SECTION" = "$WRITE_SECTION" ]; then
            # If it was, and the value wasn't written already, write it
            if [ $VALUE_WRITTEN -eq 0 ]; then
                printf "\n%s=%s" "$WRITE_KEY" "$WRITE_VALUE" >> "$INI_FILE_TEMP"
                VALUE_WRITTEN=1
            fi
        fi
        printf "\n[%s]" "$1" >> "$INI_FILE_TEMP"
        
        LAST_SECTION="$1"
    }
    
    __shini_parsed_comment__writer()
    {
        printf ";%s" "$1" >> "$INI_FILE_TEMP"
    }
    
    __shini_parsed__writer()
    {
        if [ "$1" = "$WRITE_SECTION" ]; then
            if [ "$2" = "$WRITE_KEY" ]; then
                if [ ! -z "$WRITE_VALUE" ]; then
                    printf "\n%s=%s" "$WRITE_KEY" "$WRITE_VALUE" >> "$INI_FILE_TEMP"
                fi
                VALUE_WRITTEN=1
                return
            fi
        fi
        
        printf "\n%s=%s" "$2" "$3" >> "$INI_FILE_TEMP"
    }
    
    if [ $# -lt 3 ]; then
        if shini_function_exists "__shini_no_file_passed"; then
            __shini_no_file_passed
        else
            printf 'shini: Argument 1 needs to specify the INI file to write.\n' 1>&2
            exit 254
        fi
    fi
    
    INI_FILE="$1"
    INI_FILE_TEMP="$(mktemp -t shini_XXXXXX)"       
    
    WRITE_SECTION="$2"
    WRITE_KEY="$3"
    WRITE_VALUE="$4"
    LAST_SECTION=""
    VALUE_WRITTEN=0
    
    shini_parse "$1" "_writer" "$2" "$3" "$4"
    # Still not written out yet
    if [ $VALUE_WRITTEN -eq 0 ]; then
        # Check if final existing section was target one, add it if not
        if [ "$LAST_SECTION" != "$WRITE_SECTION" ]; then
            printf "\n[%s]" "$WRITE_SECTION" >> "$INI_FILE_TEMP"
        fi
        # Write value at end of file
        printf "\n%s=%s" "$WRITE_KEY" "$WRITE_VALUE" >> "$INI_FILE_TEMP"
    fi
    
    mv "$INI_FILE_TEMP" "$INI_FILE"
    
    # ********
    shini_teardown
}

# default usage
__shini_parsed()
{
    if [[ $2 != *\$* ]] && [[ $3 != *\$* ]]; then
        eval $2=$3
    fi
}

__shini_parse_error()
{
    error_line=$1
}

__shini_parse_error__writer()
{
    error_line=$1
}
